yew ,Spccici< of Fossil^ frovi Oliio. 221 



middle of the dissepiment, as well us in the more slender, finer 

 and more direct, and much more crowded rays, also in having 

 a larger number of somewhat smaller \wvc% on the rays. Mr. 

 Meek, loc. cit., identifies the above species with Synocladia 

 (^esfriensis {Sepfipovfc Ccdriensis, Prout, Trans. Sr. Louis Acad. 

 Sci., Vol. I, ]). 448, pi. 18, fi'x. i), which differs frcmi the Ohio 

 siiecimeiis in the stronger and thicker, as well as more flexuose 

 rays ; in the rounded fenestrules. and smaller-sized pores, which 

 are also more abundant, often showing three raiiges on parts be- 

 low bifurcations. On direct comp uison of the T\ewtonville spe- 

 cimens with specimens from (Miester, 111., these difterences, 

 esjjeciall}' those jiertaining to the mode of growth, are very 

 marked and characteristic. 



Formation and Locality. — In the Maxvi le limestone (Ches- 

 ter), at jN'ewtonville, Ohio. Coiled ed by Pi'of. E. B. Andrews. 



LAMELLIBRANCHIATA. 

 Pinna ITlaxvillcnsis, u. sp. 



Pal. O., Vol. Ill, Plate 10, Fig. 5. 



Shell of about a medium size, very acutelj^ triangular in outline, with 

 highly convex valves ; the length along the hinge equal to nearly three 

 times the greatest width. Hinge-line straight, not quite as long as the shell 

 below ; anterior end acute ; basal margin very slightly arcuate, and the pos- 

 terior extremity rather broadly rounded ; the point of greatest length being 

 at about one-third of the width below the hinge-line. Surface of the shell, 

 except for a short distance within the basal margin, marked hj moderately 

 strong, simple radiating plications, about eighteen in number, as counted 

 at the posterior end of the specimen figured, but increasing in number with 

 increased growth ; the additions being near the hinge. There are also nu- 

 merous strong concentric lines of growth parallel to the margin, often form- 

 ing undulations of the surface. 



I find no American species described that closely resembles 

 this one ; but P. flexicostata, McCoy, from the English Carboni- 

 ferous rocks (British Pal. Foss., p. 499, pi. 3, E, figs. 11—13), 

 is very similar, but has slightly stronger radii, is somewhat 

 broader, and differs in having a longitudinal depression just be- 

 low the hinge-line, which this sjiccies does not j^ossess. 



Formation and Locality. — In the Maxville limestone, at Max- 

 ville, Ohio. Collection of Prof. E. B. Andrews. 



